A device for forming a barrier in an annulus of a well

ABSTRACT

A device is for forming a barrier in an annulus of a well. The device has an injection tool adapted to introduce a polymeric hardening liquid in through an opening in the annulus, and a pump unit adapted to provide pressure to said liquid so that the liquid is introduced into the opening in the annulus with a controllable pressure. The device has a control unit adapted to control the pump unit so that said liquid is provided into the opening with an initial pressure at a start-up phase of introducing the liquid into the opening and a final pressure at a close-down phase of introducing the liquid into the opening, wherein the final pressure is higher than the initial pressure.

INTRODUCTION

The present invention relates to a device for forming a barrier in anannulus of a well, such as a hydrocarbon or water injector well. Thedevice comprises an injection tool adapted to introduce a polymerichardening liquid in through an opening in the annulus, and a pump unitadapted to provide pressure to said liquid so that the liquid isintroduced into the opening in the annulus with a controllable pressure.

The present invention further relates to an arrangement and a method forforming a barrier in an annulus of a well.

PRIOR ART

In various situations, an annulus of a well needs to be remediallyrepaired in order to provide the required and necessary annulus sealingcapabilities. The annulus of the well is located between two pieces ofpipes, tubing-casings or casing to casing. The annulus can also bebetween the said tubing/casing and the wellbore formation. The purposeof the casings are for example to isolate different zones of the well,or to function as a well barrier to the surface.

In prior art, the annulus isolation are formed by either cement, anothersealing material or by a mechanical packer being part of the initialwell completion. A challenge with a cemented annulus is that it can leakwater or hydrocarbons in between the zones, or to the surface via thecemented annulus. Prior art devices for repairing a leaking cementedbarrier is called a cement squeeze and comprising a method where cementis squeezed into the annulus to repair the failed barrier. To repair aleaking packer is by traditional means not possible.

Prior art method of forming barriers by means of a polymeric hardeningliquid, such as various types of resins are known. However, it has alsoproven to be difficult to form barriers using such resins with highreliability.

WO2010/147476A1 discloses a well tool and a method for forming a barrierin a well using a resin.

SUMMARY OF THE INVENTION

The invention has for its object to remedy or to reduce at least one ofthe drawbacks of the prior art, or at least provide a useful alternativeto prior art. The object is achieved through features, which arespecified in the description below and in the claims that follow.

The object of the invention is to provide an improved device for forminga barrier in an annulus of a well. In particular, an object of theinvention is to provide a device that enables a barrier to be formed inan annulus of a well subjected to a differential pressure with improvedreliability.

This object is provided by means of a device for forming a barrier in anannulus of a well according to the invention. The device comprises

-   -   an injection tool adapted to introduce a polymeric hardening        liquid in through an opening in the annulus, and    -   a pump unit adapted to provide pressure to said liquid so that        the liquid is introduced into the opening in the annulus with a        controllable pressure.

The device is characterized in that it comprises a control unit adaptedto control the pump unit so that said liquid is provided into theopening with an initial pressure at a start up phase of introducing theliquid into the opening and a final pressure at a close-down phase ofintroducing the liquid into the opening, wherein the final pressure ishigher than the initial pressure.

The injection tool is configured to introduce a polymeric hardeningliquid in through the opening in the annulus when forming the barrier.The pump unit is adapted to provide pressure to the liquid so that theliquid is introduced in through the opening with a pressure. The controlunit is adapted to control the pressure in which the pump unitintroduces the liquid in through the opening in the annulus.

By means of introducing the polymeric hardening liquid in through theopening in the annulus during a period of time in which the pressure ofintroducing the liquid from the start up phase to the close-down phaseis increased, the quality of the formed barrier is improved. Thepolymeric hardening liquid relates to a polymeric based liquid that ishardening with time, i.e. the viscosity of the hardening liquidincreases from a pumpable liquid to a none pumpable paste, and being asolid at the final stage.

It is believed that by introducing the liquid at a low pressure at thestart-up phase when the liquid has low viscosity, and subsequentlyintroducing the liquid at a high pressure at the close-down phase whenthe liquid has a high viscosity, allows the liquid to first penetrateinto the larger cracks of the annulus, and thereafter fill up thesmaller volume of the cracks, whereby a barrier of high quality isformed. The “low” and “high” in the previous sentence is to be regardedas relative terms. The viscosity is lower at the start-up phase than atthe close-down phase as the liquid is hardening with time. The pressureis lower at the start-up phase than at the close-down phase.

According to an embodiment of the invention, the control unit is adaptedto control the pump unit so that said liquid is provided into theopening with a gradual increasing pressure over time from the start upphase to the close-down phase of introducing the liquid to the openingin the annulus.

The device is in particular preferably for forming a barrier in anannulus comprising a cement material. However, it shall be understoodthat the device may be applied to an annulus filed with other types ofsolids.

According to an embodiment of the invention, the initial pressure isbetween 1-50 bar, preferably between 10-30 bar.

According to an embodiment of the invention, the final pressure isbetween 2-400 bar, preferably between 30-250 bar.

According to an embodiment of the invention, the control unit adapted tocontrol the pump unit between the start up phase and the close-downphase of introducing the liquid to the opening at a time period betweenone hour and 72 hours, preferably between 12 and 48 hours.

According to an embodiment of the invention, the device furthercomprises a device for forming said opening in the annulus. The devicefor forming said opening comprises for example a perforation unit or adrill unit.

According to an embodiment of the invention, the control unit adapted tocontrol the pump unit so that said liquid is provided into the openingin the annulus with two or more injection sequences with increasingpressure.

The object of the invention is further obtained by means of anarrangement for forming a barrier in a concrete annulus of a well. Thearrangement comprises the device according to any of above embodimentsand a polymeric hardening liquid.

According to an embodiment of the invention, said liquid has a viscositybetween 5-1*10{circumflex over ( )}6 cP at the start up phase ofintroducing the liquid to the opening, preferably a viscosity of between15 20000 cP.

According to an embodiment of the invention, said liquid has a viscositybetween 1*10{circumflex over ( )}6-10*10{circumflex over ( )}6 cP at theclose down phase of introducing the liquid to the opening, preferablybetween 2*10{circumflex over ( )}6-5*10{circumflex over ( )}6 cP.

According to an embodiment of the invention, said liquid mainlycomprises a thermoset material.

The object of the invention is further obtained by means of a method forforming a barrier in a concrete annulus of a well. The method comprises:

-   -   positioning an injection tool at a position of an opening in the        annulus for introducing a polymeric hardening liquid,    -   at a start up phase, introducing the liquid into the opening at        a initial pressure, and    -   at a close-down phase, introducing the liquid into the opening        at a final pressure, wherein the final pressure is higher than        the initial pressure.

According to an embodiment of the invention, the method comprises:

-   -   gradual increasing pressure over time from the start up phase to        the close-down phase of introducing the liquid into the opening        in the annulus.

According to an embodiment of the invention, the initial pressure isbetween 1-50 bar, preferably between 10-30 bar.

According to an embodiment of the invention, the final pressure isbetween 2-400 bar, preferably between 30-250 bar.

According to an embodiment of the invention, a time period between thestart up phase and the close-down phase of introducing the liquid to theopening is between one hour and 72 hours, preferably between 12 and 48hours.

According to an embodiment of the invention, the method comprisesproviding said liquid into the opening in the annulus with two or moreinjection sequences with increasing pressure.

BRIEF DESCRIPTION OF DRAWINGS

In the following is described examples of preferred embodimentsillustrated in the accompanying drawings, wherein:

FIG. 1 discloses a schematic view of device for forming a barrier in anannulus of a well according to an embodiment of the invention;

FIG. 2 discloses a schematic view of a well comprising an annulus to beprovide with a barrier by means of the device in FIG. 1;

FIG. 3 discloses a flow chart of a method for forming a barrier in anannulus of a well according to an embodiment of the invention;

FIG. 4 discloses a flow chart of a method for forming a barrier in anannulus of a well according to a further embodiment of the invention;and

FIG. 5 discloses a flow chart of a method for forming a barrier in anannulus of a well according to yet another embodiment of the invention.

DETAILED DESCRIPTION

In FIG. 1 is a schematic view of device 1 for forming a barrier in anannulus 5 of a well according to an embodiment of the inventiondisclosed. FIG. 1 also discloses an arrangement 10 comprising the device1 configured with a polymeric hardening liquid.

The device 1 comprises an elongated structure to be inserted in the well11, such as a hydrocarbon or water injector well.

In FIG. 2 is a schematic view of a well 11 comprising the annulus 5 tobe provided with a barrier by means of the device 1 in FIG. 1. The well11 comprises a well head 12 and a first casing 14 and second casing 16concentric between which an annulus 5 is formed that has been filledwith a solid, such a solid comprising a cement material or othersuitable material. The device 1 is adapted to be introduced into thewell 11.

For example, in FIG. 2, a part of the annulus 5 is filled with a goodcement column, another part of the annulus 5 is filled with poor cementcolumn, and yet another part of the annulus 5 is without filling. Theannulus 5 is to be provided with one or several barriers by means of thedevice 1 in FIG. 1.

The device 1 comprises an injection tool 20, a device 22 for forming theopening into the annulus 5, a reservoir 24 for containing the polymerichardening liquid and a pump unit 26.

The device 22 for forming the opening in the annulus 5 comprises forexample a drill unit comprising a drive unit and a drill bit fordrilling through the first casing 14 and into the annulus 5. The device22 for forming the opening in the annulus 5 comprises alternatively aperforation unit.

The injection tool 20 is adapted to introduce the polymeric hardeningliquid in through an opening in the annulus 5. The injection tool 20comprises an outlet adapted to be aligned with the opening in theannulus 5 for providing the liquid into the opening.

The pump unit 26 is configured to provide pressure to the liquid so thatthe liquid is introduced into the opening in the annulus 5 with acontrollable pressure. The pump unit 26 comprises for example ahydraulic induced pump or an electric induced pump.

The device 1 further comprises a control unit 30 adapted to control thepump unit 26 and accordingly the pressure in which the liquid isintroduced into the opening in the annulus 5. The control unit 30adapted to control the pump unit 26 so that said liquid is provided intothe opening with an initial pressure at a start up phase of introducingthe liquid into the opening and a final pressure at a close-down phaseof introducing the liquid into the opening. The final pressure is higherthan the initial pressure. Accordingly, the control unit 30 is adaptedto control the pump unit 26 so that the liquid is introduced at a lowpressure when the liquid has a low viscosity at the start-up phase offorming the barrier and at a high pressure when the liquid has a highviscosity at the close-down phase when forming the barrier. The “low”and “high” in the previous sentence is to be regarded as relative termsfor the purpose of explaining the invention. Details on parameters forforming will be explained in connection with the explanation of themethod.

The control unit 30 comprises a logic unit, such as a CPU, adapted toexecute a computer program, and signalling means connected to the pumpunit 26 for controlling the pressure of introducing the liquid into theopening in the annulus 5. It shall be understood that the control unit30 comprises the necessary features for controlling the pressure ofintroducing the liquid into the opening in the annulus 5 during a periodof time of forming the barrier.

In the disclosed embodiment in FIG. 1, the device 1 comprises thecontrol unit 30 and further control means 31 for controlling the controlunit 30 from the surface. The further control means 31 is for example acomputer unit comprising a CPU adapted to execute a computer program.The further control means 31 is connected to the control unit 30, whichin the disclosed embodiment is located in vicinity of the pump unit 26.

Preferably, the polymeric hardening liquid comprise mainly a thermosetmaterial. The liquid has preferably the characteristic in form aviscosity between 5-2000 cP at the start up phase of introducing theliquid to the opening, preferably a viscosity of between15-1*10{circumflex over ( )}6 cP. Furthermore, the liquid has preferablythe characteristic in form a viscosity between 1*10{circumflex over( )}6-10*10{circumflex over ( )}6 cP at the close down phase ofintroducing the liquid to the opening, preferably between2*10{circumflex over ( )}6-5*10{circumflex over ( )}6 cP.

The invention will now be explain in view of a method for forming abarrier in an annulus 5 of a well 11. It shall be understood that thecontrol unit 30 of above discussed device 1 is configured to control thedevice 1 accordingly.

In FIG. 3 is a flow chart of a method for forming a barrier in anannulus 5 of a well 11 according to an embodiment of the inventiondisclosed.

The method comprises, in a step 110, positioning an injection tool 20 ata position of an opening in in the annulus 5 for introducing thepolymeric hardening liquid.

In a step 120, the method comprises, at a start-up phase, introducingthe liquid into the opening at an initial pressure. Subsequently, in astep 130, the method comprises, at a close-down phase, introducing theliquid into the opening at a final pressure, wherein the final pressureis higher than the initial pressure.

According to a preferred embodiment, the method comprises introducingthe liquid into the opening at the initial pressure between 1-50 bar,preferably between 10-30 bar.

According to a preferred embodiment, the method comprises introducingthe liquid into the opening at the final pressure is between 2-400 bar,preferably between 30-250 bar.

According to a preferred embodiment, the duration between the start upphase and the close-down phase of introducing the liquid to the openingis between one hour and 72 hours, preferably between 12 and 48 hours.

In FIG. 4 is a flow chart of a method for forming a barrier in anannulus 5 of a well 11 according to a further embodiment of theinvention disclosed. The method in FIG. 4 differs from the method inFIG. 3 in that the method further comprises, in a step 125, graduallyincreasing the pressure of the liquid over time from the start up phaseto the close-down phase of introducing the liquid into the opening.

In FIG. 5 is a flow chart of a method for forming a barrier in anannulus 5 of a well 11 according to yet another embodiment of theinvention disclosed. The method in FIG. 5 differs from the method inFIG. 3 in that the method further comprises, in a step 127, providingsaid liquid into the opening in the annulus 5 with two or more injectionsequences with increasing pressure.

It shall be understood that the method in FIG. 3-5 may also involve thestep of forming the opening into the annulus 5 if the opening into theannulus 5 has not yet been established.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.Use of the verb “comprise” and its conjugations does not exclude thepresence of elements or steps other than those stated in a claim. Thearticle “a” or “an” preceding an element does not exclude the presenceof a plurality of such elements. The mere fact that certain measures arerecited in mutually different dependent claims does not indicate that acombination of these measures cannot be used to advantage.

1. A device for forming a barrier in an annulus of a well, the devicecomprising: an injection tool adapted to introduce a polymeric hardeningliquid in through an opening in the annulus, and a pump unit adapted toprovide pressure to said liquid so that the liquid is introduced intothe opening in the annulus with a controllable pressure, wherein thedevice comprises a control unit adapted to control the pump unit so thatsaid liquid is provided into the opening with an initial pressure at astart up phase of introducing the liquid into the opening and a finalpressure at a close-down phase of introducing the liquid into theopening, wherein the final pressure is higher than the initial pressure.2. The device according to claim 1, wherein the control unit is adaptedto control the pump unit so that said liquid is provided into theopening with a gradual increasing pressure over time from the start upphase to the close-down phase of introducing the liquid into the openingin the annulus.
 3. The device according to claim 1, wherein the initialpressure is between 1-50 bar, preferably between 10-30 bar.
 4. Thedevice according to claim 1, wherein the final pressure is between 2-400bar, preferably between 30-250 bar.
 5. The device according to claim 1,wherein the control unit adapted to control the pump unit between thestart up phase and the close-down phase of introducing the liquid to theopening at a time period between one hour and 72 hours, preferablybetween 12 and 48 hours.
 6. The device according to claim 1, wherein thedevice further comprises a device for forming said opening in theannulus.
 7. The device according to claim 1, wherein the control unitadapted to control the pump unit so that said liquid is provided intothe opening in the annulus with two or more injection sequences withincreasing pressure.
 8. An arrangement for forming a barrier in anannulus of a well, wherein the arrangement comprises a device and apolymeric hardening liquid, the device comprising: an injection tooladapted to introduce a polymeric hardening liquid in through an openingin the annulus, and a pump unit adapted to provide pressure to saidliquid so that the liquid is introduced into the opening in the annuluswith a controllable pressure, wherein the device comprises a controlunit adapted to control the pump unit so that said liquid is providedinto the opening with an initial pressure at a start up phase ofintroducing the liquid into the opening and a final pressure at aclose-down phase of introducing the liquid into the opening, wherein thefinal pressure is higher than the initial pressure.
 9. The arrangementaccording to claim 8, wherein said liquid has a viscosity between5−1*10{circumflex over ( )}6 cP at the start up phase of introducing theliquid to the opening, preferably a viscosity of between 15-20000 cP.10. The arrangement according to claim 8, wherein said liquid has aviscosity between 1*10{circumflex over ( )}6-10*10{circumflex over ( )}6cP at the close down phase of introducing the liquid to the opening,preferably between 2*10{circumflex over ( )}6-5*10{circumflex over ( )}6cP.
 11. The arrangement according to claim 8, wherein said liquid mainlycomprises a thermoset material.
 12. A method for forming a barrier in anannulus of a well, the method comprises: positioning an injection toolat a position of an opening in the annulus for introducing a polymerichardening liquid, at a start up phase, introducing the liquid into theopening at an initial pressure, and at a close-down phase, introducingthe liquid into the opening at a final pressure, wherein the finalpressure is higher than the initial pressure.
 13. The method accordingto claim 12, wherein the method comprises: gradual increasing pressureover time from the start up phase to the close-down phase of introducingthe liquid to the opening.
 14. The method according to claim 12, whereinthe initial pressure is between 1-50 bar, preferably between 10-30 bar.15. The method according to claim 12, wherein the final pressure isbetween 2-400 bar, preferably between 30-250 bar.
 16. The methodaccording to claim 12, wherein a time period between the start up phaseand the close-down phase of introducing the liquid to the opening isbetween one hour and 72 hours, preferably between 12 and 48 hours. 17.The method according to claim 12, wherein the method comprises providingsaid liquid into the opening in the annulus with two or more injectionsequences with increasing pressure.